Research

 

Research in the Thornburg Laboratory is focused on a unique floral organ, the Nectary.

The nectary is responsible for secretion of floral nectar, the sweet fluid that is the primary attraction for insect pollinators. The long term goals of the Thornburg laboratory are to understand nectary development and function and to be able to manipulate these functions to achieve improved crop pollination which would result in higher rates of seed set and thereby, greater yields.

  • Understanding nectar composition
    The composition of nectar has been widely studied. Nectar is an aqueous combination of a variety of substances. Chief among these are sucrose, glucose, and fructose. At least 11 other carbohydrates have also been identified in nectars of some flowers. All twenty of the normal amino acids found in protein have also been identified in various nectars. Other substances reported in nectar include organic acids, terpenes, alkaloids, flavonoids, glycosides, vitamins, phenolics, oils, and five proteins. Our work has focused on the nectar proteins. This work has defined the Nectar Redox Cycle that functions in protecting the gynoecium from attack by microorganisms (see publications)
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  • Understanding nectary development
    Many flowering plants produce a rich floral nectar to attract insect and avian pollinators and thereby increase their fecundity. Nectar is produced by the nectary, a terminally differentiated organ often located at the base of the flower. The mechanisms of floral development that give rise to the nectary and thence to the floral nectar are completely unknown.


  • Starch metabolism in the nectary gland
     The nectar of ornamental tobacco is 35% (by weight) carbohydrate, although the source of carbohydrate in nectar is unknown. We are investigating the posibility that nectar sugars derive from starch synthesized in the nectary gland prior during floral development. Because carbohydrate may be the most important component of nectar for attracting pollinators, a clear understanding of the mechanisms required for nectar production will enable the eventual manipulation of nectar components to achieve increased yields for insect pollinated crop plants.
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  • Carotenoid metabolism in the nectary gland
     In flower buds, the tissue that will eventually develop into the nectary gland is photosynthetic (green and contains chloroplasts). However, during the development of the nectary, the nectary tissue becomes non-photosynthetic and is filled with chromoplasts (orange). These studies are designed to understand the biosynthesis of carotenoids in the nectary gland and simultaneously to understand the conversion of chloroplasts into chromoplasts.
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